One of the driving mechanisms bringing back the arctic air and the stormy weather is the MJO. This phenomena monitors convective storms that form around the world and is divided into eight phases. Phases 8-1-2 in the month of March, which is the current and foreseeable state of the MJO, bring colder than normal and stormy weather to the eastern U.S. This is one of the reasons why the drought-stricken state of California is finally able to see rain over the next few weeks.
The MJO is not the only signal jump starting our winter pattern. The EPO, as has been the case most of this winter, is back in a negative state and trending even further negative (near -4 value) by this weekend. This means blocking in the eastern Pacific, including Alaska and western Canada has formed. Additionally, the AO is also negative which does not surprise me given the extreme negative state of the EPO and the arctic air mass we are currently dealing with and will still have to deal with for the next 10 days.
Lets take a look at the players on the field and see how this storm is coming together. As I have already mentioned, we have blocking over Alaska and western Canada due to the -EPO. There is confluence caressing the U.S.-Canadian boarder with strong vorticity over the Great Lakes (will take a look at this later). Our southern short wave, which is progged to be on the weak side hence the flat-looking eastern trough, is in the southeast. One of the most important players, the Polar Vortex, will situate itself somewhere just east of the Hudson Bay in southeastern Canada. The question is...where does the baroclinic zone set-up? Areas north of this boundary will see precip. fall in the form of snow while areas south of it see rain. Areas located along the boundary could see freezing rain / sleet. Also notice near Greenland I say, "No Blocking?" Technically, this is true. However, there is blocking on the other side of the globe that has prevented the PV's this season from escaping northeastward which in turn would allow the southeast ridge to amplify over our area.
It is called Scandinavian blocking (sorry for the typo in the graphic). Positive heights over Scandinavia, or a -SCA, have helped force our PV's this winter to sink south into the lower latitudes of the globe and promote much below normal temperature departures. This feature is going to help keep the PV situated over southeast Canada for the storm early next week, though there is room for it to trend north-northeast if it wanted to.
What are the implications of that?
Here is the upper air anomaly graphic from the 00z EURO run last night:
The PV was modeled weaker last night than the 12z run today which allowed eastern heights to extend further north, allowing the gradient to get pretty far north as well. This is why the 00z EURO run last night showed significantly less snowfall for the I-95 cities compared to today's run.
You can see on today's run the PV is stronger and heights are suppressed a bit more. It may not seem like it at a quick glance, but take a closer look and you will see this minor difference changes the projected track of the storm drastically.
Another ingredient we have to consider is the vort energy located over the Great Lakes, as well as the strained out H5 energy along the east coast. Right now, the southern s/w energy is projected to be weak. But if the vort over the Great Lakes intensifies further, it could force the southern s/w to trend stronger as well which could raise QPF amounts across the board. Right now, .75-1.00 of QPF is projected to fall Sunday-Tuesday, but I could see how this gets up to 1.25+ in a widespread location. This would mean snowfall accumulations, with ratios, of 16 inches or more in some spots.
The jet streak over Maine is also expected to be impressive Monday morning, which is when the heaviest snow is expected to move into the area. 160+ kts. could really fuel this storm some more as we try and get a better idea of where the best lift at the 700mb level develops. Area JUST north of the gradient area likely to see the heaviest snow rates (but probably not the best ratios). This is why when all is said and done, everyone should receive significant snowfall from this storm.
The one thing we have to watch which is certainly plausible is the Polar Vortex continues to trend stronger on the models and begins to force this storm to our south, while also shearing it apart (less QPF). The GFS has remained the most consistent and has not showed such a solution, but the EURO / CMC runs today could be interpreted that way (the EURO because it took a big jump from its 00z run).
As of now, this is the area I see getting hit the hardest with snow early next week. This is more of a EURO ENS / GFS blend with some instinctive feeling. One of the trends this winter have been for storms to make a last minute push back to the north and west, which is why Philly has seen a very nice season in terms of snowfall. Central Park, NY is only 18.5 inches away from breaking their all-time single season snowfall record and this storm could get them VERY close to that record if everything aligns itself perfectly. I also feel the lack of blocking over Greenland could bring the PV slightly further north than where the EURO / GGEM currently have it which is another reason why I like the GFS / EURO ENS solutions.
A first call snow map will be released tomorrow afternoon around 6pm. Please follow the www.njstrongweatherforum.com for continuous coverage of this storm with the latest information!
Thanks for reading,
Francesco Paparatto
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